Java解析XML(XML模拟数据库，控制台版考试系统)

package cn.tyz.dao; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import cn.tyz.bean.Student; import cn.tyz.exception.StudentNotExcepton; import cn.tyz.utils.XmlUtils; public class StudentDao { //增加考试信息 public void add(Student stu) { try { Document document = XmlUtils.getDocument(); //创建出封装学生属性的标签 Element student_tag = document.createElement("student"); student_tag.setAttribute("idcard", stu.getIdCard()); student_tag.setAttribute("examid", stu.getExamId()); //创建用于封装学生姓名，所在地和成绩的标签 Element name = document.createElement("name"); Element location = document.createElement("location"); Element grade = document.createElement("grade"); //为标签添加值 name.setTextContent(stu.getName()); location.setTextContent(stu.getLocation()); grade.setTextContent("" + stu.getGrade()); //为各个标签元素建立父子关系 student_tag.appendChild(name); student_tag.appendChild(location); student_tag.appendChild(grade); //把封装了信息学生标签，挂到文档上 document.getElementsByTagName("exam").item(0).appendChild(student_tag); //调用自定义工具方法将更新的内容从内存中写入文件 XmlUtils.writeToXml(document); } catch (Exception e) { //将异常转型为运行时异常，再抛给上层，避免给上层带来麻烦 throw new RuntimeException(e); } } //查找考生信息 public Student find(String examId) { Student stu = new Student(); try { Document document = XmlUtils.getDocument(); //得到XML文档所有学生节点 NodeList list = document.getElementsByTagName("student"); //遍历 for(int i=0; i<list.getLength(); i++) { Element student_tag = (Element) list.item(i); if(student_tag.getAttribute("examid").equals(examId)) { stu.setExamId(examId); stu.setIdCard(student_tag.getAttribute("idcard")); stu.setName(student_tag.getElementsByTagName("name").item(0).getTextContent()); stu.setLocation(student_tag.getElementsByTagName("location").item(0).getTextContent()); stu.setGrade(Double.parseDouble(student_tag.getElementsByTagName("grade").item(0).getTextContent())); } } } catch (Exception e) { //将异常转型为运行时异常，再抛给上层，避免给上层带来麻烦 throw new RuntimeException(e); } return stu; } //删除考生信息 public void delete(String name) throws StudentNotExcepton { try { Document document = XmlUtils.getDocument(); NodeList list = document.getElementsByTagName("name"); for(int i=0; i<list.getLength(); i++) { if(list.item(i).getTextContent().equals(name)) { list.item(i).getParentNode().getParentNode().removeChild(list.item(i).getParentNode()); //调用自定义工具方法将更新的内容从内存中写入文件 XmlUtils.writeToXml(document); return; } } throw new StudentNotExcepton(name + "不存在！"); } catch (StudentNotExcepton e) { throw e; } catch (Exception e) { //将异常转型为运行时异常，再抛给上层，避免给上层带来麻烦 throw new RuntimeException(); } } }